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Gliese 49: activity evolution and detection of a super-Earth. A HADES and CARMENES collaboration
Schmitt, J. H. M. M.; Rebolo, R.; Amado, P. J. +40 more
Context. Small planets around low-mass stars often show orbital periods in a range that corresponds to the temperate zones of their host stars which are therefore of prime interest for planet searches. Surface phenomena such as spots and faculae create periodic signals in radial velocities and in observational activity tracers in the same range, s…
The tilt of the local velocity ellipsoid as seen by Gaia
Evans, N. W.; Belokurov, V.; Schönrich, R. +1 more
The Gaia Radial Velocity Spectrometer (RVS) provides a sample of 7224 631 stars with full six-dimensional phase space information. Bayesian distances of these stars are available from the catalogue of Schönrich, McMillan & Eyer. We exploit this to map out the behaviour of the velocity ellipsoid within 5 kpc of the Sun. We find that the tilt of…
The First Metallicity Study of M83 Using the Integrated UV Light of Star Clusters
Skillman, Evan D.; Hernandez, Svea; Aloisi, Alessandra +8 more
Stellar populations are powerful tools for investigating the evolution of extragalactic environments. We present the first UV integrated-light spectroscopic observations for 15 young star clusters in the starburst M83 with a special focus on metallicity measurements. The data were obtained with the Cosmic Origins Spectrograph on board the Hubble S…
The host galaxies of FeLoBAL quasars at z ∼ 0.9 are not dominated by recent major mergers
Villforth, C.; Hamann, F.; Hamilton, T. +4 more
Theoretical models have suggested an evolutionary model for quasars, in which most of luminous quasars are triggered by major mergers. It is also postulated that reddening as well as powerful outflows indicate an early phase of activity, close to the merger event. We test this model on a sample of quasars with powerful low-ionization outflows seen…
The SOFIA Massive (SOMA) Star Formation Survey. II. High Luminosity Protostars
Tanaka, Kei E. I.; Zhang, Yichen; Tan, Jonathan C. +6 more
We present multiwavelength images observed with SOFIA-FORCAST from ∼10 to 40 µm of seven high luminosity massive protostars, as part of the SOFIA Massive Star Formation Survey. Source morphologies at these wavelengths appear to be influenced by outflow cavities and extinction from dense gas surrounding the protostars. Using these images, we …
The relation between the turbulent Mach number and observed fractal dimensions of turbulent clouds
Klessen, Ralf S.; Federrath, Christoph; Schneider, Nicola +1 more
Supersonic turbulence is a key player in controlling the structure and star formation potential of molecular clouds (MCs). The three-dimensional (3D) turbulent Mach number, M, allows us to predict the rate of star formation. However, determining Mach numbers in observations is challenging because it requires accurate measurements of the velocity d…
A Discrete Set of Possible Transit Ephemerides for Two Long-period Gas Giants Orbiting HIP 41378
Omohundro, Mark; Vanderburg, Andrew; Hellier, Coel +22 more
In 2015, K2 observations of the bright (V = 8.9, K = 7.7) star HIP 41378 revealed a rich system of at least five transiting exoplanets, ranging in size from super-Earths to gas giants. The 2015 K2 observations only spanned 74.8 days, and the outer three long-period planets in the system were only detected with a single transit, so their orbital pe…
NuSTAR Measurement of Coronal Temperature in Two Luminous, High-redshift Quasars
Brandt, W. N.; Bianchi, S.; Cappi, M. +13 more
X-ray emission from the active galactic nucleus (AGN) is believed to be produced via Comptonization of optical/ultraviolet seed photons emitted by the accretion disk, upscattered by hot electrons in a corona surrounding the black hole. A critical compactness versus temperature threshold is predicted above which any increase in the source luminosit…
On the Nature of the Bright Core of Solar Coronal Mass Ejections
Chen, Y.; Song, H. Q.; Cheng, X. +5 more
Coronal mass ejections (CMEs) often exhibit the classic three-part structure in a coronagraph, i.e., the bright front, dark cavity, and bright core, which are traditionally considered as the manifestations of coronal plasma pileup, magnetic flux rope (MFR), and filament, respectively. However, a recent survey based on 42 CMEs all possessing the th…
The Pristine survey - VII. A cleaner view of the Galactic outer halo using blue horizontal branch stars
McConnachie, Alan W.; Martin, Nicolas; Venn, Kim A. +11 more
We use the Pristine survey CaHK narrow-band photometry, combined with the Sloan Digital Sky Survey (SDSS)ugr photometry, to provide a cleaner sample of blue horizontal branch stars in the Galactic halo out to large distances. We demonstrate a completeness of 91 per cent and a purity of 93 per cent with respect to available spectroscopic classifica…